A checkPermission() for a matching URLPermission (done by the http
handler) would stop walking the access-control context (acc) stack at that
doPrivileged() invocation and succeed. A check for a non-matching
URLPermission or some other permission, however, would match the JRE class's
generally assigned privileges and continue walking the full acc stack as if the
limited doPrivileged() had not been invoked.

These limited privileges are also captured by getAccessControlContext() and
by thread inheritance.